Homogeneous tandem catalysis of the bis(diphenylphoshino)amine-chromium oligomerization catalyst with the metallocenes Ph2C(Cp)(9-Flu)ZrCl2 and racEtIn(2)ZrCl(2), is discussed. GC, CRYSTAF, and C-13 NMR analysis of the products obtained from reactions at constant temperatures show that during tandem catalysis, alpha-olefins, mainly 1-hexene and 1-octene, are produced from ethylene by the oligornerization catalyst and subsequently built into the polyethylene chain. At 40 degrees C the Cr/PNP catalyst acts as a tetramerization catalyst while the polymerization catalyst activity is low. Copolymerization of ethylene and the in situ produced a-olefins have also been carried out by increasing the temperature from 40 degrees C, where primarily oligomerization takes place, to above 100 degrees C, where polymerization becomes dominant. The melting temperature of the polymer is dependent on the catalyst and cocatalyst ratios as well as on the temperature gradient followed during the reaction, while the presence of the oligomerization catalyst reduces the activity of the polymerization catalyst. (c) 2006 Wiley Periodicals, Inc.